This invention relates to commercial trailers towed in tandem behind a truck-trailer and more particularly to a pup trailer dolly back-up direction guide for positioning the pup trailer dolly under the forward end portion of a semitrailer to be towed.
1. Field of the Invention
A commercial truck-trailer, where permitted frequently tows a second semitrailer which is frequently referred to as a "pup trailer".
A fifth wheel dolly, commonly referred to as a "pup trailer dolly", towed by a truck-trailer is disposed under the forward end portion of the trailing semitrailer for supporting the latter in mobile fashion.
During normal trucking operations it is frequently necessary for the driver of the truck-trailer to park the trailing semitrailer or pup trailer and remove the pup trailer dolly from under its forward end portion and recouple the pup trailer dolly to another semitrailer for towing behind the truck-trailer.
This is normally a difficult and time consuming operation for a lone truck driver since the mass of the pup trailer dolly is approximately one ton. The driver must decouple the safety chains, electrical system and air brake lines connected with the pup trailer dolly and manually back or manipulate the pup trailer dolly into a selected position at the front or forward end portion of the semitrailer to be coupled.
The forward end of the pup trailer dolly is centrally connected to the rearward end of the towing semitrailer in trailer hitch fashion by a pintle hook.
Since the overall dimensions of the pup trailer dolly are relatively small when compared with the overall dimensions of the semitrailer of a truck-trailer unit, it is a difficult, if not impossible, operation for the driver to observe its position and direction and back a truck-trailer and pup trailer dolly into fifth wheel coupling position of the dolly at the forward end of a second semitrailer.
After manually positioning the pup trailer dolly at the forward end of a second semitrailer to be towed, the driver backs the truck-trailer into position for connection with the pup trailer dolly. The dolly is pintle hook connected with the forward semitrailer and moved rearwardly by the truck-trailer under the forward end portion of the second semitrailer where the fifth wheel on the dolly receives, in locking relation, the fifth wheel pin depending from the second semitrailer. The safety chains, electrical system and air brake lines are again connected for over-the-road travel.
Even with ideal weather conditions and hard surface truck terminal yards valuable time and fuel is consumed in changing a pup trailer dolly from towing one semitrailer to proper coupled position for towing a different semitrailer.
The above problems in transferring a pup trailer dolly from one semitrailer to another are minimized by this invention which temporarily eliminates the pivotal action between a towing truck-trailer and positions a pup trailer dolly for backing the dolly with a truck-trailer as a unit, into position at the forward end portion of a second semitrailer to be towed.
2. Description of the Prior Art
I do not know of any patents disclosing a pup trailer dolly backing direction guide such as is disclosed by this invention.